The present invention relates generally to miniature microscope system. More particularly, the present invention relates to GRIN (“graded index”) lens microscope system which allows for magnification of an object in a video microscope system without the large cumbersome impairments of existing video microscope systems.
An important tool for research as well as diagnosis of medical problems is the optical microscope. A conventional optical microscope includes an objective lens and an imaging lens. Exemplary microscopes include objective and imaging lenses that are compound lenses or lens systems. Both objective and imaging lenses contribute to image magnification. The objective lens forms a first magnified image of an object being examined. The first image becomes the object for the imaging lens which produces a further magnified final image. The total magnification is the product of the separate magnifications produced by the objective lens and the imaging lens. The two lenses are utilized to reduce optical aberrations, particularly chromatic aberrations and spherical aberrations. Chromatic aberration is the phenomenon of different colors focusing at different distances from a lens which produces soft overall images, and color fringing at high-contrast edges, like an edge between black and white. Use of an optical microscope to examine internal tissues of a large animal typically entails removing the tissues from the animal. The removal facilitates positioning the microscopes objective lens for viewing the tissues.
To record or photograph images from an optical microscope, a digital camera may be optically and mechanically adapted to the microscope. An adapter connects the camera with the microscope. A firm mechanical connection is particularly important, because even the smallest movements (vibrations) of the camera strongly reduce the image quality. Furthermore, the light path must be optically adapted so that a fully lit, focused image is projected to the camera sensor (CCD/CMOS). There are several methods for attaching a digital camera to a microscope. One solution is to use the phototube. Using the adapter, the digital camera is screwed firmly onto the tube. The two oculars continue to be used for the visual observation of the specimen. Unfortunately, almost all microscopes that are equipped with a phototube are very costly. Another option is to directly place a digital camera, without any adaptations, directly to the ocular, and to capture an image with a steady hand. Due to the lack of optical adaptation, however, this method produces a smaller, vignetted image in most cases wherein the edges of an image are darker than the center. This effect causes only a small part of the sensor to be optimally used; the rest remains black. A more professional, but also more costly solution is to use a tube adapter. With this method, the ocular is removed and an adapter is fitted into the phototube with the digital camera. The adapter acts as a mechanical and optical interface between microscope and digital camera. This makes it possible to avoid motion blurs due to camera shake and vignettation effects, leading to a much higher quality of the image.